Touch Panel, also known as Touch Screen or Touch Control Panel, is an induction type display device that is able to receive input signal from a contactor or the like, and it is widely used in various electronic products. According to different operation principles and information transmitting media, there are four types of Touch Panels: resistance type, capacitive type, infrared ray type, and surface sound wave type.
Capacitive Touch Panel (abbreviated as CTP) controls the screen by utilizing electric current induction of a human body. On the basis of detected change of electric capacity of the contacted area, the location of the contacting finger is calculated with accuracy up to 99% and respond time less than 3 ms. Since CTP has advantages such as high sensitivity and easily achievable multi-point touch control, CTP gradually becomes a mainstream Touch Panel applied in electronic products such as smart-phones and tablet computers.
In prior art, according to the relative position between the touch control stacked layer structure and the display panel, CTP can be divided into different technical architectures of out-cell (the touch control device is hanging out of the display panel), on-cell (the touch control device is configured on the display panel), and in-cell (the touch control device is integrated within the display panel). Although the out-cell technology and the on-cell technology are mature and have been widely used along with medium and small sized display panel, and OFS (One Film Solution) of the out-cell technology can be used in an organic electro-luminescent display device to make it possible for flexible touch control display, however, the in-cell technology can make the display panel lighter and thinner, with higher light transmittance and lower power consumption, as well as achievable flexibility, and therefore the in-cell technology is considered to be an ultimate solution for touch control display, especially for touch control of organic electro-luminescent display, which will gradually become a development mainstream of touch control technology in organic electro-luminescent display devices.
Chinese patent literature CN102830827A discloses a touch control display device and preparation method thereof, wherein the touch control display device comprises a first touch control sensing layer formed on the surface of an upper substrate, an organic light-emitting component formed on the surface of a lower substrate, and a composite layer formed by a combination of sensing electrodes and organic light-emitting electrodes. In this touch control display device, the second sensing electrodes that originally belongs to a second touch control sensing layer and the opposite electrodes that originally belongs to an opposite electrode layer of the organic light emitting component are mixed or combined in a single layer. Because the first sensing electrodes and the second sensing electrodes are respectively formed in the first touch control sensing layer and in the composite layer, an insulation layer is required to be arranged between these two layers. As such, the overall complexity of the preparation steps can be reduced, and the manufacturing yield of the product can be effectively increased.
In the above-mentioned touch control display device, although the thickness of the touch control display device can be reduced to a certain extent by mixing the second sensing electrodes and the opposite electrodes in a single layer, however, as the other part of the touch control device, the first touch control sensing layer is still required to be arranged on the surface of the upper substrate, therefore, this touch control display device still pertains to an out-cell structure which inevitably has the problems of large thickness and low light transmittance.
More importantly, in this patent literature, the second sensing electrodes and the organic light-emitting electrodes are combined in a single layer, which easily causes a problem of signal cross-talk and thus has severe adverse influence on the display quality of the touch control display device. Besides, in the first embodiment of this patent literature, there is no physical insulation layer provided between the first sensing electrodes and the second sensing electrodes, and as a result, in order to ensure insulation between the first sensing electrodes and the second sensing electrodes, not only a sufficient insulation space needs to be retained between the first sensing electrodes and the second sensing electrodes, which leads to that the thickness of the touch control display device cannot be further reduced, but also the upper substrate must have very little flexibleness, so as to prevent the first sensing electrodes from touching the second sensing electrodes, therefore, this touch control display device cannot be made flexible or with a large dimension. In another embodiment of this patent literature, the first sensing electrodes are arranged on the upper surface of the upper substrate, i.e. the first sensing electrodes and the second sensing electrodes are respectively arranged on two sides of the upper substrate, and as a result, although the problem of inability to achieve flexibility and large dimension as in the first embodiment can be avoided, however, the vertical distance between the first sensing electrodes and the second sensing electrodes is too long, which has severe adverse influence on the sensitivity of touch control; furthermore, in order to protect the first sensing electrodes from being damaged by external force, a protection layer is inevitably required to be formed above the first sensing electrodes, which adds to the complexity of the preparation steps, further increases the thickness of the touch control display device, lowers the light transmittance, and also adversely affects the aesthetic appearance of the touch control display device.